1. Technical Field of the Invention
With high speed machine tools, there is a desire to damp vibrations resulting from, for example, acceleration and deceleration of machine components along the machine""s axes of motion or from chatter vibrations inherent in the cutting process. One known method of damping such vibrations includes attaching a damper mass assembly to the machine component to be damped, and tuning the frequency of the response of the damper so that it is close to the frequency of the unwanted vibration of the machine component.
In some cases, it is desired to provide damper tuning on the component at more than one vibration frequency, or in more than one principal direction. In such cases, there is a desire to retain the attached damper mass in proper position and to provide flexibility in the damper""s ability to act in the proper direction(s). The present invention relates to a tuned damped absorber support providing simultaneous energy dissipation in both horizontal and vertical directions which also provides for proper mass position retention.
2. Brief Description of the Related Art
Prior art vibration damping systems that are used to address more than one vibration frequency or more than one principal direction have generally utilized either multiple damper mass assemblies applied independently or damping elements applied in preselected, fixed orientations on a single damper mass to act in both shear and compression. Rods are found in the prior art to hang a damping mass that is required to have a vertical shear plane. This rod hanging application freely allows damping action in the horizontal direction along the shear plane, but renders any damping action in the vertical direction ineffective.
The following U.S. patent references are cited: U.S. Pat. No. 5,871,315, Burt et al., issued Feb. 16, 1999, for a tombstone fixture; U.S. Pat. No. 5,058,261, Kitamura, issued Oct. 22, 1991, for a machine tool; U.S. Pat. No. 5,033,340, Siefring, issued Jul. 23, 1991, for an apparatus and method for tool vibration damping; U.S. Pat. No. 4,921,378, Kytola, issued May 1, 1990, for a rotary-pallet system; U.S. Pat. No. 4,669,227, Treppner, issued Jun. 2, 1987, for an angle plate apparatus with precisely adjustable workpiece holder; U.S. Pat. No. 4,630,811, Rudisill, issued Dec. 23, 1986, for a model fixturing apparatus; U.S. Pat. No. 4,512,068, Piotrowski, issued Apr. 23, 1985, for a pallet receiver with compliant pin and socket registration; U.S. Pat. No. 4,468,019, Staudenmaier, issued Aug. 28, 1984, for a pallet clamping system for machine tools; U.S. Pat. No. 4,438,599, Kamman et al., issued Mar. 27, 1984, for a vibration damper for machine-carried workpiece; U.S. Pat. No. 3,790,153, Seidenfaden, issued Feb. 5, 1974, for equipment for holding workpieces; U.S. Pat. No. 3,522,864, Richter, issued Aug. 4, 1970, for a tuned damper assembly for machine tools; U.S. Pat. No. 3,447,402, Ray, issued Jun. 3, 1969, for a damped tuned boring bar; and, U.S. Pat. No. 2,714,823, Dall et al., issued Aug. 9, 1955, for a vibration damper.
The present invention relates to a tuned damped absorber support assembly for machine tools providing simultaneous energy dissipation in at least two directions of motion to attenuate vibrations of the machine tool resulting from machine operation. The tuned damped absorber assembly of the present invention, oftentimes referred-to herein as an xe2x80x9cattachment assemblyxe2x80x9d, is attached directly or indirectly to a machine component requiring damping. Both single damper mass and double damper mass configurations are shown. With a double damper mass, the system can easily be tuned to two different frequencies by independent adjustment of the damping elements. The single damper mass is typically applied for tuning of a single frequency, but could also be tuned for two different frequencies by providing a support rod with non-symmetric cross section.
Even more particularly, the preferred embodiment of the present invention is an attachment assembly to be attached to a machine component to accomplish energy dissipation simultaneously in both a horizontal direction and a vertical direction, where the attachment assembly comprises a damper mass having a rod bore therethrough from a bushing face to a component face, the rod bore having a threaded bushing receiving portion extending from the bushing face toward the component face and a rod receiving portion extending from the component face toward the bushing face; the damper mass having at least one preload bore therethrough from the bushing face to the component face; at least one damping element preload assembly including a cap screw having a threaded end, a spring retainer, a preload spring, and a damping element, the cap screw having the spring retainer and the preload spring inserted thereon, the cap screw received by the at least one preload bore with the threaded end extending therefrom on the component face, the cap screw having the damping element inserted thereover to abut the component/plate face; a bushing having a throughbore and a threaded outer portion; a rod having a threaded component end and an opposed lock nut end, the lock nut end having a threaded portion and an adjacent bushing receiving shaft portion, the bushing receiving shaft portion having an adjacent enlarged bushing stop portion toward the component end; the rod received by the rod bore in the damper, the component end of the rod bore extending therefrom on the component face, the bushing received over the lock nut end of the rod to abut the enlarged bushing stop portion with the bushing threaded outer portion threadably received by the threaded bushing receiving portion of the rod bore. This assembly can be attached directly or indirectly to the machine component.
According to one aspect of the present invention, an attachment assembly for dissipating energy of a moving machine component is provided, wherein the attachment assembly dissipates energy of the moving machine member in at least two directions of motion.
According to another aspect of the present invention, an attachment assembly for attenuating vibrations of a machine component is provided, comprising means for dissipating energy of the machine component in at least two directions.
According to yet another aspect of the present invention, an attachment assembly for dissipating energy of a moving machine component is provided, comprising at least one damper mass, at least one first preload assembly, each of the first preload assemblies having a first end coupled to the damper mass by a biasing element and a second end coupled to the machine component, at least one rod for mounting the at least one damper mass to the machine component and for applying a preload to the at least one first preload assembly, and at least one first damping element.
According to one embodiment of the present invention, an attachment assembly for dissipating energy of a moving machine component is provided, comprising at least a first damper mass and at least a second damper mass.